CVE-2026-98737
Description
A flaw was found in the Linux kernel's Bluetooth subsystem. This flaw allows a local user to cause a Denial of Service (DoS) or potentially escalate privileges due to a use-after-free condition. The issue arises from a race condition where synchronous command routines access inquiry cache entries without proper locking, allowing a concurrent cache flush request to free memory that is still actively in use.
Statement
A race in the Bluetooth HCI inquiry cache can cause a slab use after free because synchronous command workers look up an inquiry entry and read its fields without holding hdev lock. A concurrent local HCIINQUIRY ioctl can flush the cache and free the entry before hci_acl_create_conn_sync or hci_stop_discovery_sync finishes using it. KASAN confirms reads from freed slab memory and the immediate demonstrated consequence is a kernel crash. For the CVSS the PR:L reflects that a local process needs access to Bluetooth HCI control operations which may require delegated CAP_NET_RAW or CAP_NET_ADMIN but does not necessarily require unrestricted root access. AC:H applies because reliable triggering depends on winning a race window between cache lookup and cache removal. The issue is not directly reachable by a remote network peer alone. A nearby Bluetooth device may affect inquiry cache contents but local control is still needed to flush the cache and drive the competing synchronous path. Impact is at least a local denial of service via kernel crash and in the paranoid worst case may include confidentiality or integrity impact due to reuse of freed slab memory.
Mitigation
Mitigation for this issue is either not available or the currently available options don't meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 4.7 | N/A | N/A |
| Attack Vector | Local | N/A | N/A |
| Attack Complexity | High | N/A | N/A |
| Privileges Required | Low | N/A | N/A |
| User Interaction | None | N/A | N/A |
| Scope | Unchanged | N/A | N/A |
| Confidentiality | None | N/A | N/A |
| Integrity Impact | None | N/A | N/A |
| Availability Impact | High | N/A | N/A |
Vector
Red Hat: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
Understanding the Weakness (CWE)
Integrity
Technical Impact: Modify Memory
The use of previously freed memory may corrupt valid data, if the memory area in question has been allocated and used properly elsewhere.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
If chunk consolidation occurs after the use of previously freed data, the process may crash when invalid data is used as chunk information.
Confidentiality
Technical Impact: Read Memory
Read operations on freed memory can sometimes leak sensitive information instead of causing a crash
Integrity,Confidentiality,Availability
Technical Impact: Execute Unauthorized Code or Commands
If malicious data is entered before chunk consolidation can take place, it may be possible to take advantage of a write-what-where primitive to execute arbitrary code. If the newly allocated data happens to hold a class, in C++ for example, various function pointers may be scattered within the heap data. If one of these function pointers is overwritten with an address to valid shellcode, execution of arbitrary code can be achieved.
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